SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ff03f9cf2eb81fac007e080ef32c6f3805ee1a4fcbad36b7e43edded9bb99b2' 
  AND token = 'siu6BJdH9maJnCMsJLVoqY8LNPBIThO/r4o8XwANldw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}